A traffic amount handled in radio communication service has increased rapidly in recent years. A user now can download large scale data such as music data and video streaming data from a network on a radio channel. Capacity of a cellular communication system has been improved to achieve a peak data rate of 100 Mbps or higher in downlink by introduction of long term evolution (LTE) which is positioned as 3.9th generation. In the fourth generation mobile phone service which is scheduled to be in practical use around 2015, it is expected that a data rate of 1 Gbps at a maximum in a semi-fixed environment and 100 Mbps at a maximum in a mobile environment can be achieved. However, because development of a cellular communication system does not catch up with increase of traffic, there still remains a risk of local degradation of a data rate due to increase of system load and occurrence of a network failure. Non-Patent Literature 1 proposes active utilization of a small cell as one of measures against such a risk.
While macro cells which have a relatively large cell size, are disposed adjacent to each other so as to cover a wide geographical region, small cells are normally disposed so as to locally cover a location where a radio wave of the macro cell is weak or traffic concentrates. A small cell can be used to complement radio communication service by a macro cell or provide specific service. A terminal hands over from a macro cell to a small cell, so that the terminal can achieve more favorable communication quality and a higher data rate.
However, when the number of small cells operating within a service area of a macro cell increases, radio signals from more near cells act on a radio signal of one cell as interference. Therefore, it is desirable that a base station of the small cell refrains from transmitting a signal as much as possible under circumstances where there is no terminal within the own cell or a high data rate is not requested. For example, Patent Literature 1 proposes a technique of stopping transmission of a radio signal from a small cell base station under circumstances where there is no terminal in the vicinity.